Live cells in suspension can be sorted according to optical properties such as fluroescence and light scattering using fluorescence-activated cell sorters (FACS). The prototypes for these instruments were developed in this laboratory. They will be used for various applications including isolation of fetal cells from the blood of pregnant women for possible prenatal diagnostic tests; analysis and sorting of live lymphoid cell populations for functional studies. The combinations of fluorescein, rhodamine and other fluorochromes will be used to tag monoclonal antibodies which recognize cell surface antigens characteristic of subpopulations of T and B lymphocytes. A time resolved two-laser illumination system for FACS will be used for some of these studies. Planned improvements in design of FACS instruments include: individual cell sorting (cloning), multi-sample injection systems, and ultra-fast laser beam deflection to increase detection sensitivity.